This invention relates to a snorkel for use by a swimmer.
The basic principal of a snorkel for a swimmer has been known for a long time. A snorkel has a mouthpiece and a tube which extends upwards from the mouthpiece in use. It enables a swimmer to swim submerged for extended periods of time. A wide variety of different snorkel designs have been proposed. In particular, many of these designs address the problem of unwanted water entry into the snorkel. However, at the present time, there is no satisfactory solution to the problem of unwanted water entry. Indeed, the most common type of snorkel design simply ignores this problem, and has a plain upright tube, into which water can enter. The user or swimmer then has the problem of discharging or eliminating water as it enters the snorkel tube.
An early proposal of a swimming mask, including a snorkel-type tube is to be found in U.S. Pat. No. 859,787 (Steenerson). The overall construction is quite complex. It includes a swimming mask that is intended to form a sealing fit with a person's head, and two valves. To the applicant's knowledge, this somewhat complex and cumbersome design has never been in commercial usage.
A breathing apparatus for swimmers is disclosed in the Wilen U.S. Pat. No. 2,317,236. Of interest is the provision of a check valve at the top of the snorkel tube. It essentially comprises a lightweight ball, which will float on water, and a cage retaining the ball. In use, if water approaches the top of the snorkel tube, the intention is that the ball will be pressed upwards against the seat, to prevent unwanted water entry. However, whilst this type of check valve construction has been employed in many snorkels, it has been found to have numerous disadvantages. In the context of a simple snorkel, it is relatively complex, and can be damaged. Further, the check valve does not always seal reliably, when required. It is quite easy for small quantities of water to enter the snorkel tube. This is particuarly the case, when swimming in water with small, choppy waves. If the ball does rise to close off the tube, when the swimmer is attempting to inhale, then the partial vacuum created by inhalation will hold the ball in place, even if the water then falls away from the ball. Consequently, it requires a conscious effort on the swimmer's part to release this pressure, before commencing inhalation. At best, this is extremely inconvenient. Here, it is effectively acknowledged that the check valve will not prevent entry of water into the snorkel tube. The snorkel construction disclosed also includes a flap-type valve at its lower end. It is stated that this valve is to enable any saliva, or water shipped accidentally, to be purged from the snorkel. The valve is opened, either by the swimmer manually closing the check valve at the top to enable sufficient pressure to be built up, or by the swimmer raising the flap-valve out of the water. The swimmer can then blow out any accumulated saliva, water etc. This procedure is complex and inconvenient.
In U.S. Pat. No. 4,066,077 (Shamlian), there is disclosed a snorkel construction. This patent is primarily concerned with the construction of the mouthpiece, but it dislcoses a simple snorkel construction, which is currently quite popular.
Another snorkel construction is disclosed in U.S. Pat. No. 4,071,024 (Blanc). This construction is quite complex. It also addresses the problem of unwanted water entry. For this purpose, separate inhalation and exhalation tubes are provided. Additionally, a spiral vein is provided around the top of the intake or inhalation tube, to at least retard entry of water. The exhalation tube is shorter and is provided with a one-way flap at its other end. To purge water from the snorkel, a portion of the inhalation tube has to be manually collapsed, so that water can be blown out of the exhalation tube.
A somewhat unusual design of diving snorkel is disclosed in the Schuch U.S. Pat. No. 4,278,080. Here, a purge valve is located in a branch or by-pass conduit. This valves enables water in the snorkel to automatically fall to the level of the surrounding water surface. It is suggested that this minimizes the amount of water required to be purged from the snorkel. This suffers from the disadvantage of requiring a valve, which opens in to the water, and which might leak. Again, as with other designs, one has the problem of actually purging the water from the snorkel, which can be difficult for small quantities of water.
In German Pat. No. 868,058, there is disclosed a somewhat cumbersome snorkel construction. It is suggested that the main part of the snorkel is made from glass. It includes an air tube having an upper flared end, and a short tube connecting the air tube to a mouth-piece and a water sack. The water sack is intended for the collection of sweat, saliva and other fluids, but is rigid and has to be inverted to be emptied. It is also stated that the end of the air pipe or tube must always be above water, and that it must be extended for deeper diving. It is thus not intended for use in the same way as a conventional snorkel, where one can submerge for periods allowing the snorkel to fill up with water while submerged.
Italian Pat. No. 401,363 addresses the problem of diving to depths where the length of the air pipe can result in a significant buffer zone of air that is continuously inhaled and exhaled. To this end, a through-flow air supply system is provided, including a small, floating air pump.
Italian Pat. No. 590,401 discloses a snorkel, in which provision is made for entry of unwanted water. For this purpose, at the bottom of the snorkel, two conduits are provided, one above the other. Consequently, if the lower conduit becomes blocked with water, a clear passage is still provided through the upper conduit. It is suggested that, with both passageways full of water, the user can exhale, to displace water from both passageways and the main air inlet tube. It seems questionable whether this would work. Also, in use, as the snorkel slowly fills up with small quantities of water, the user has to wait until both passageways are blocked with water, before attempting to expel the water. Until both passageways are blocked, the user or swimmer cannot generate sufficient back pressure to empty them. Consequently, one will at some stage have the situation where the lower passageway is filled, and the upper passageway is partly filled, but insufficiently filled to enable the user to expel the water. It is then highly likely that water will be accidentally entrained in inhaled air, leading to choking, coughing. Also, as the shipped water is retained in the lower passageway, which is in full communication with the upper passageway, it is quite likely that sudden movement of the swimmer will also cause water to be entrained in inhaled air.
It will thus be appreciated that, despite numerous attempts, there is currently no satisfactory solution to the problem of water accidentally entering a snorkel. Small quantities of water entrained into the inhaled air can cause choking, coughing, spluttering etc of the swimmer. At best, this is extremely inconvenient. In some circumstances it can be quite dangerous. Further, it is extremely distracting for the swimmer, to have to always be mentally alert for the possibility of water being drawn in when he inhales. Preferably, a snorkel should be such that the swimmer can be reasonably confident that he can breathe freely, without inhaling any water.
In known snorkel designs, as disclosed in the Shamlian U.S. Pat. No. 4,066,077, it is a relatively easy matter to expel a large quantity of water. Where there is sufficient water to completely block the snorkel, then the user or swimmer can generate sufficient back pressure, to expel this water as a plug. Problems arise, where there is a small quantity of water, insufficient to block the snorkel. If it is left in the snorkel, the swimmer is then subject to gurgling etc as he inhales, with the real possibility that some of this water might be inhaled. Expelling this small quantity of water is difficult. It can only be expelled by means of short, sharp exhalations, which effectively force the water out by viscous or like effects. Frequently, it requires a number of short, sharp breaths to clear such a small quantity of water, and inevitably not all of it is removed.
Accordingly, a snorkel should both prevent any accidentally shipped water reaching the user or swimmer, and also enable the swimmer to readily expel the water.